Thursday night's event in Houston illustrated the high-stakes race for the Republican presidential nomination. Rubio, coming off second-place finishes in the South Carolina primary and Nevada caucus, came out more aggressive than he has in the past, going head-to-head with Trump and winning accolades from the audience along the way.

Immigration dominated the night's discussions.

Trump addressed comments made by former Mexican President Vincente Fox's about the real estate mogul's plan to build a Mexican border wall at Mexico's expense.

"If he builds the wall the way he built Trump Tower, he'll be using illegal immigrant labor to do it," he said, repeating information stemming from a New York Times report that revealed Trump's Florida club largely employs foreign workers.

"If he hadn't inherited $200 million, do you know where Donald Trump would be? Selling watches in Manhattan," Rubio added, capping off a stream of attacks against Trump.

The two went at it again over the possibility of repealing President Barack Obama's executive action to grant deferred status for children of undocumented immigrants. Trump accused Rubio of lying after the Florida senator addressed the topic.

"You lied to the students of Trump University," Rubio fired back, referring to a fraud lawsuit against Trump's unaccredited, for-profit real estate school. Trump may be called to testify in court over the lawsuit during the home stretch of primary season.

Cruz also piled on the attacks against Trump. In a later argument, Trump told Cruz, "I know politicians better than you do."

"I funded you," Trump interrupted. "I funded this guy, I gave him a check."

Rubio interjected: "He never funded me."

"You know why?" Trump responded. "I didn't want you."

Things became even more heated when a three-way shouting match broke out between the three top-polling candidates.

CNN moderator Wolf Blitzer shouted over the three, "Gentlemen you have to stop this!"

Cruz tried: "Donald, relax."

"I'm relaxed," Trump said. "You're the basket case."

Kasich made several pleas with the three front-runners to keep things civil, and at one point, bemoaning his lack of talking time, Carson asked, "Can somebody attack me, please?"

Trump is coming off three wins in a row in the New Hampshire and South Carolina primaries and Nevada caucuses. While polls show Cruz may have the home-turf advantage in Texas, his lead is in the single digits at 7 percent, according to the 30-day Real Clear Politics average of all polls.

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